It is well known that many biological products, for example, proteins such as enzymes, are produced by the culturing of certain organisms (yeast, bacteria, fungi) in appropriate nutrient media under suitable conditions. After culturing or fermenting the organisms to produce the desired product, one needs to recover the product from the fermentation broth. This recovery process can be problematic, particularly when done on a large commercial scale. Problems can be encountered due to the large volume of broth produced, the viscosity of the broth, the cells and cellular debris present in the broth, the solubility of the desired product, etc. These problems are well understood by those active in the field.
Many recovery processes for biological/fermentation products have been developed. For example, EP Patent 0 214 531 B1 describes a recovery process for extracellular enzymes from whole fermentation broth comprising adding a mixture of a polymer, such as polyethylene glycol, and a salt. Likewise, U.S. Pat. No. 4,144,130 describes a recovery process for enzymes from intact cells and cell fragments using either a polymer-salt mixture or a multi-polymer system. These processes and many others known in the art are not commercially attractive for large scale recovery of commodity products, primarily because of the need to develop efficient recycling operations for regenerating high cost polymers (extractants) used in such processes, in order to economically recover the products on a continuous basis. EP 0 574 050 A1 discloses methods for recovery and purification of hydrophobic fermentation products. However, this process is useful only for hydrophobic fermentation products and does not employ high HLB surfactants as does the present invention. Therefore, there is a need for a more economical large scale recovery process for recovering products (and particularly hydrophilic products) from fermentation broths.
An improved process has been developed and is described herein, which is a surfactant-based extraction process. This process is particularly useful for the recovery of fermentation products such as enzymes to be used in detergent formulations ("detergent-type enzymes"), because detergent formulations already incorporate a large amount of surfactant. Furthermore, the surfactant-based extraction process is particularly useful for the extraction of hydrophilic products, which heretofore have not been recovered into surfactants by extraction. Thus, for example, one could recover a detergent-type enzyme such as a relatively hydrophilic alkaline protease by extracting the enzyme from its fermentation broth (clarified or whole) using a surfactant which is compatible with the ultimate detergent formulation for which the detergent-type enzyme is destined. This recovery process results not only in very high yields of enzyme recovery, but also in reduction of the overall cost of producing the product since the cost of the surfactant used in the enzyme recovery process is offset by the reduction of necessary surfactant to be added by the formulator making the detergent end product.